The cobalt-rare earth magnets developed in recent years possess such great magnetic strength as to make moving magnet transducers a distinct practical possibility. My U.S. Pat. No. 3,798,391 discloses and claims electro-acoustic transducers utilizing cobalt-rare earth intermetallic compounds as moving-magnet members.
My U.S. Pat. application, Ser. No. 451,482, filed Mar. 15, 1974, describes and claims a moving-magnet loudspeaker in which the permanent magnet element has a circular configuration. The parts forming such a loudspeaker could be assembled with much less manual adjustment and care than was necessary for the conventional moving-coil type of loudspeaker.